CODEWITHSUNDEEP
androidmemorybundle
Ryhan
Ryhan

Reputation: 1885

Android onSaveInstanceState Bundle

When android kills your process due to system constraints it gives you the ability to persist data across processes by storing the data in a bundle. Where is this bundle saved if your process is killed? Which process does it live in? Where in memory does it live in? Does it live in kernel memory?

Upvotes: 2

Views: 326

Answers (1)

ucsunil
ucsunil

Reputation: 7494

Kernel memory is a protected memory space where only critical code like the kernel code reside. This is to prevent interference of data from the user and that of the kernel and also for other performance and design reasons. Kernel memory will persist through a reboot.

The data being persisted in the Bundle is passed in the method of the onSaveInstanceState() - before the user leaves the Activity not before the Activity gets destroyed. This likely means that the memory is not written in a static memory area like the memory card. The Bundle will indeed be persisted but in a more dynamic way.

While this question has not been directly answered, it looks like this is memory on the RAM. When you look at the performance of Android devices, the more recent devices with more RAM seem to be capable of holding on to apps for much longer

From the official documentation at http://developer.android.com/training/basics/activity-lifecycle/recreating.html, it is understood that this memory is tracked by Android itself.

By default, the system uses the Bundle instance state to save information about each View object in your activity layout (such as the text value entered into an EditText object). So, if your activity instance is destroyed and recreated, the state of the layout is restored to its previous state with no code required by you. However, your activity might have more state information that you'd like to restore, such as member variables that track the user's progress in the activity.

To save additional data about the activity state, you must override the onSaveInstanceState() callback method. The system calls this method when the user is leaving your activity and passes it the Bundle object that will be saved in the event that your activity is destroyed unexpectedly. If the system must recreate the activity instance later, it passes the same Bundle object to both the onRestoreInstanceState() and onCreate() methods.

Also keep in mind that this Bundle gets destroyed when the device shuts down. Android might have a specially designed memory area for this but either way it is somewhere in the RAM.

Upvotes: 2

Related Questions